Detection reagents that can be evaluated photometrically typically induce a color change, the intensity of which depends on the analyte concentration. Such measuring systems make it possible to easily determine an analyte concentration in a bodily fluid sample, typically blood and/or interstital fluid. Important analyte concentrations that can be determined using such measuring systems are glucose concentration, cholesterol concentration, or lactate concentration, for example.
An advantage of a measuring and lancing device is that a bodily fluid sample obtained by way of lancing can be fed to a test field without any additional action on the part of a user. Lancing elements can be used, for example, which comprise a channel which takes up bodily fluid by way of capillary forces. Such a channel can lead to a test field disposed on the lancing element or can be used to transfer sample to a separate test field, e.g. by pressing a test field against a section of the channel designed as a groove. A further possibility for automatic sample take-up is known from WO 2008/083844 A1, for example, and involves placing a test field next to a lanced site using a suitable device mechanism.
Due to the automatic sample take-up, the operation of a measuring and lancing device is relatively simple and there is hardly any risk that a bodily fluid sample will become contaminated on the way to the test field. In addition, a concentration determination can be carried out even using very small sample quantities that are insufficient to wet a test field completely. To ensure that the photometric determination of concentration is not corrupted by light from unwetted test field regions, it is known from U.S. Pat. No. 6,249,593 to detect the test field using a detector array in a very large number of pixels and, by way of image evaluation, to remove pixels of unwetted regions to prevent interference signals. However, additional improvements in this area of technology are needed.